The invention relates to a coating apparatus with a high sputtering or deposition rate, having a magnet system in which magnetic lines of force emerging from the cathode face and returning thereto form a discharge area in conjunction with an electrical field.
A cathode sputtering apparatus with a high sputtering rate is already known (German Pat. No. 24 17 288), in which the cathode to be sputtered, which faces the substrate to be sprayed, is plate-shaped, so that the substrate can be moved close to the discharge area across the planar sputtering surface and parallel to the latter, while the magnet system producing the magnetic field is disposed on the side of the cathode facing away from the planar sputtering surface.
This known cathode, however, has the disadvantage that, in the case of very large substrates, such as windowpanes for example, no really satisfactory uniformity of the coating on the substrate can be achieved. Moreover, the ablation of the target is such that only a relatively small proportion of the sputterable material on the target contributes to the formation of the coating on the substrate, since the sputtering of the material is very intensive at narrowly limited portions of the plate-shaped target but takes place hardly at all at portions adjacent thereto.
It is the purpose of the present invention to improve the life of the target and thereby the ablation of the target material and to permit a very uniform coating even of especially large-area substrates. Furthermore, in the case of a plasma-supported CVD process, a good uniformity of the coating thickness on the substrate is to be achieved.